Category: Graphene Oxide

Improve safety with flame retardant polymeric compounds with graphene oxide

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Improve safety with flame retardant polymeric compounds

with graphene oxide

Polymeric compounds (engineering plastics) are widely used in the automotive, construction, food, aerospace and other sectors. Its use is based on the weight/resistance ratio, physical stability, chemical resistance and corrosion resistance.

However, most polymers, due to their nature, are flammable and combustible. That is, they are materials that catch fire quickly when exposed to fire, undergoing degradation, Veo complicadoand releasing heat to later start the propagation of the flames. During the combustion of polymers, they release smoke (soot) and toxic gases that are a danger to the safety of human life and property.

Four key components are involved during the combustion of polymeric materials: heat, oxygen, fuel, and free radical reaction. Flame retardancy of polymeric composites can be achieved by inhibiting or perturbing one or more of these components.

In recent years, multiple investigations have been carried out to develop additives that help inhibit or reduce the flammability of polymers, these additives are known as flame retardants.

Conventional flame retardants can be classified into two main categories, based on their components: inorganic flame retardants and organic flame retardants. The first include hydroxide, metal oxide, phosphate, silicate among others. They have excellent thermal stability, are non-toxic, are low cost and do not produce pollution. However, inorganic flame retardants are limited by high loading, low compatibility, and aggregation. On the other hand, organic flame retardants include flame retardants containing halogens, phosphorous, phosphorous-nitrogen, etc. The latter have high efficiency and good compatibility with polymers. Their main disadvantage is that they are restricted because they can release toxic gases and be harmful during combustion, endangering the health of people and the environment.

Graphene oxide (GO) is currently the most novel nanomaterial for use as a flame retardant because it exhibits high efficiency as a retardant with low loads and is non-toxic. Its efficiency is associated with the fact that graphene oxide has a strong barrier effect, high thermal stability and great surface absorption capacity, which are favorable for reducing heat and mass transfer.

Graphene-based flame retardants can improve the flame resistance of polymers by inhibiting the two key terms: heat and fuel. More specifically, graphene oxide can function as a flame retardant in different synergistic ways.

  1. First of all, GO has a unique two-dimensional layer structure and can promote the formation of a continuous dense layer of carbon during the combustion process. Carbon can act as a physical barrier to prevent heat transfer from the heat source and delay the escape of products (pyrolysis) from the polymeric substrate.
  2. Second, GO has a large specific surface area and can effectively adsorb flammable volatile organic compounds or hinder their release and diffusion during combustion.
  3. Third, GO contains abundant reactive oxygen-containing groups (carboxyl group at the edges, as well as epoxy and hydroxyl groups at the basal planes in the sheets). For example, oxygen-containing groups can undergo decomposition and dehydration at low temperatures, thus absorbing heat and cooling the polymeric substrate during combustion. Meanwhile, the gases generated by dehydration can dilute the oxygen concentration around the ignition periphery, decreasing the risk of fire spread.
  4. It can also modify the rheological behavior of the polymer and prevent its dripping, thus hindering the release and diffusion of volatile decomposition products through the ”maze effect” and affecting the flame retardancy of compounds (for example, modifying the UL-94 classification, oxygen index (OI) and time to ignition (TTI).

In studies carried out, it has been found that the incorporation of functionalized graphene oxide (5% by weight) in Polypropylene (PP) increased the Young’s modulus and the elastic limit of PP by 53% and 11%, respectively. While in the results of the flammability test (UL-94), it indicates that the presence of GO produces a change in the behavior of the melt and prevents the material from dripping.

On the other hand, the preparation of polymeric compounds in melt blending (extrusion) of Polystyrene/GO have been reported, where it was found that GO (5%) can promote carbonization on the polymer surface (layer of carbonized material). and inside, the presence of a load or filler that presents high resistance to heat and contributes to the formation of carbon residues, improving the flame resistance of polystyrene-based compounds.

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in research and production of graphene materials for the development of applications at an industrial level, through its Graphenergy Masterbatch line, has developed a wide range of masterbatches with graphene oxide, based on various polymers, such as PP, HDPE, LDPE, PET and PA6.

The incorporation of graphene and graphene derivatives (GO) to polymeric matrices has allowed the development of polymeric compounds with better mechanical properties, greater thermal stability, gas barrier capacity and reduced flammability of polymeric compounds.

References

  1. Han Y, Wu Y, Shen M, Huang X, Zhu J, Zhang X. Preparation and properties of polystyrene nanocomposites with graphite oxide and graphene as flame retardants. J Mater Sci 48:4214.
  2. Hofmann D, Wartig K-A, Thomann R, Dittrich B, Schartel B, Mu¨lhaupt R. Functionalized graphene and carbon materials as additives for melt-extruded flame retardant polypropylene. Macromol Mater Eng 298:1322.
  3. Dittrich B, Wartig K-A, Hofmann D, Mu¨lhaupt R, Schartel B. Flame retardancy through carbon nanomaterials: carbon black, multiwall nanotubes, expanded graphite, multi-layer graphene and graphene in polypropylene. Polym Degrad Stab 98:1495.

Innovation in the plastics industry: how graphene masterbatches are changing the game

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Innovation in the plastics industry:

how graphene masterbatches are changing the game

Graphene has extraordinary electrical, optical, thermal properties and high mechanical resistance. The properties of graphene are attributed to its structure in the form of two-dimensional (2D) sheets, formed by hexagonal bonded carbon atoms and a thickness of one carbon atom.

Today, graphene is the most promising nanotechnological additive in the plastics industry. The incorporation of graphene and its derivatives (graphene oxide, GO) in different polymer matrices (masterbatches), have great potential for a wide range of applications. The graphene masterbatch can act as a mechanical reinforcement or conductive additive for both thermoplastic and thermosetting materials. They can be used in the automotive, aerospace, electronics or packaging sectors.

Graphene-based polymeric compounds have shown significant improvements in properties such as elastic modulus, tensile strength, impact resistance, electrical conductivity, resistance to UV radiation, thermal stability, antimicrobial property, impermeability or barrier effect (it does not allow the diffusion of moisture or other molecules).

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in research and production of graphene materials for the development of applications at an industrial level, through its Graphenergy Masterbatch line, has developed and sells a wide range of masterbatches with graphene, based on various polymers, such as PP, HDPE, LDPE, PET and PA6.

Our Masterbatches are granular materials that act as multifunctional additives. The incorporation of graphene in different polymer matrices has shown important effects on the properties and processing conditions of plastics, among which are:

  • Increased resistance to tension, deformation and impact
  • Increased resistance to ultraviolet rays
  • Excellent dispersion
  • Improves processing conditions (thermal stability)
  • Acts as a nucleating agent (modification of the crystallization temperature of the polymer)

In this sense, it has been found that the incorporation of graphene and its derivatives, as well as the concentration, can modify the physicomechanical properties of the polymer to be processed. The addition of masterbatch to different polymers has improved the final characteristics of the material to a lesser or greater extent, for example:

  • Additivation of Polypropylene (PP) with polypropylene-graphene masterbatch (MB-PP/GO), increases tensile strength (8%) and rupture percentage (29%).
  • Additivation of Polyethylene (PE) with polyethylene-graphene masterbatch (MB-PE/GO), improves tensile strength (17%), flexural strength and rupture strength (66%).
  • Additivation of Polyethylene terephthalate (PET) with polyethylene terephthalate-graphene masterbatch (MB-PET/GO), improves resistance to humidity, increases tensile strength (72.2%) and improves impact resistance.
  • Additivation of Polycarbonate (PC) with polycarbonate-graphene masterbatch (MB-PC/GO), improves resistance to humidity and improves resistance to rupture (276%).

On the other hand, graphene masterbatches can also be incorporated into recycled polymers. Currently, the reuse and recycling of plastic materials are of vital importance in the transition path towards a circular economy. In this regard, the constant washing, pelletizing and reprocessing can cause the loss of physicomechanical properties of recycled plastics, therefore, by adding graphene, these properties can be restored or improved. In agricultural applications, mulch films with increased resistance to ultraviolet radiation can be produced.

References

  1. Fang, M., et al., Covalent polymer functionalization of graphene nanosheets and mechanical properties of composites. Journal of Materials Chemistry. 19(38): p. 7098-7105.
  2. Kim, H., A.A. Abdala, and C.W. Macosko, Graphene/Polymer Nanocomposites. Macromolecules. 43(16): p. 6515-6530.
  3. Balandin, A.A., et al., Superior Thermal Conductivity of Sin gle-Layer Graphene. Nano Letters, 8(3): p. 902-907.
  4. Nabira Fatima, Umair Yaqub Qazi, Asim Mansha., Recent developments for antimicrobial applications of graphene-based polymeric composites: A review, https://doi.org/10.1016/j.jiec.2021.04.050

Innovation in corrosion protection: graphene oxide technology

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Innovation in corrosion protection:

graphene oxide technology

Corrosion is the greatest challenge that many industries in the world must face. Currently, there is a wide variety of coatings on the market for protection against corrosion. However, most of these coatings do not have the physicochemical characteristics necessary for good performance. These coatings does not have perfect barriers and eventually fail, their chemical resistance depends on their impermeability to chemical substances, and with it their resistance to abrasion and their adhesion capacity.

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in the research and production of graphene materials for the development of industrial applications, has a wide range of coatings through its Graphenergy line.

Graphenergy is the line of nanotechnological coatings with graphene oxide, which has a complete portfolio of high-performance anticorrosive coatings for Industrial and Infrastructure maintenance.

Taking into account that the infrastructure or industrial equipment may be exposed to environments with different degrees of corrosion (intermediate or extreme), the use of Coating Systems for corrosion protection is recommended, Graphenergy offers the following alternatives:

1. ALKYD SYSTEM

Recommended for intermediate or mild corrosion environments (intermediate corrosive or aggressive conditions). This system is weather resistant and provides anticorrosive protection.

This system is made up of a primer and alkyd-type enamel, ideal for the protection of metal surfaces and industrial infrastructure, both for interiors and exteriors. Provides high anticorrosive protection, resistance to UV rays and provides extraordinary adherence to the substrate. It is recommended for non-coastal areas or where humidity conditions are not high.

2. EPOXY-POLYURETHANE SYSTEM

Designed for severe or critical environments, in which the infrastructure or equipment and/or some other protected element is exposed to UV rays and an industrial atmosphere with high contamination (highly corrosive vapors).

This system is made up of an epoxy primer and Polyurethane (finish). Coatings designed for the protection of metal surfaces exposed to highly corrosive and chemical environments. Both coatings offer high adhesion, extraordinary chemical resistance, high abrasion resistance, resistance to UV rays, and impermeability, to improve the life of any metal surface or installation and reduce maintenance costs.

Graphenergy anticorrosive coating systems have many benefits, which include:

  • Higher performance than existing coating technologies on the market today.
  • Fewer applied coating layers are required and with higher anti-corrosion protection.
  • Coatings with greater adherence to the substrate.
  • Coatings with greater chemical resistance and high thermal resistance.
  • Coatings with greater impermeability and non-stick effect.

When a coating system is selected, the influence of the environment to which it will be exposed and the final appearance that is sought and some other considerations that the system must perform, and its maintenance must be taken into account.

On the other hand, another decisive factor that determines the selection of the first anticorrosive to be used and consequently the coating system is the physical state of the metal surface to be coated and/or the surface treatment or preparation that can be given.


Referencias

  1. Fengjuan Xiao, Chen Qian, et al., et al., Progress in Organic Coatings, 125, 79-88 (2018); doi.org/10.1016/j.porgcoat.2018.08.027
  2. Karolina Ollik and Marek Lieder. Review of the application of graphene-based coatings as anticorrosion layers. Coatings 2020, 10(9), 883. 2020.
  3. Zhang J., Kong, G., Li S., Le Y., Che C., Zhang S., Lai D., Liao X. Graphene-reinforced epoxy powder coating to achieve high performance wear and corrosion resistance. 20:1448-4160, 2020.

Graphene oxide: the new ally of primary coatings in corrosion protection

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Graphene oxide:

the new ally of primary coatings in corrosion protection

Corrosion is an electrochemical reaction that occurs when the metal reacts with the surrounding environment forming ferric oxide, causing the metal to lose its main characteristics of hardness and resistance. Oxygen, temperature, humidity, contaminants, gases, and the physicochemical characteristics of water are the main factors that affect the rate at which metals corrode.

One of the most widely used methods to control corrosion is the application of protective (primer) coatings to metal surfaces. The coating forms a barrier between the substrate (metal) and the surrounding medium, retarding the deterioration or oxidation of the metal. The coatings are polymer-based substances (paints), resistant to degradation, which are used to cover the material to be protected.

Nowadays, a wide variety of primers have been developed based on different types of resin, such as the alkyd and epoxy type. Efficiency is generally associated with an increase in cost. Unfortunately, most of these coatings or paints are not perfect barriers and eventually fail due to holes or micropores in the coating or the diffusion of oxygen and water through it (they are not completely waterproof). On the other hand, the coatings continue to have low thermal resistance and above all a limited chemical resistance.

Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in the research and production of graphene materials for the development of industrial applications, through its Graphenergy line, has launched a range of primers and other nanotechnological coatings.

Graphenergy anticorrosive primers are coatings based on graphene oxide (GO), a new nanotechnological additive that provides multiple properties to coatings, including extraordinary corrosion protection and barrier technology (barrier effect). Graphene oxide creates pathways that are very tortuous, which prevents oxygen and water molecules from diffusing through the coating and eventually reaching the metal surface, providing protection against corrosion (Fig. 1). These primaries can act as mentioned, by (1) forming a barrier, which greatly prevents the penetration of oxygen and water molecules, or (2) the inhibition of the corrosion process, by increasing the electrical and ionic resistivity, cutting the corrosion cycle.

Fig. 1 Mechanism of anticorrosive protection of coatings based on polymers and graphene.

Among the anticorrosive primers that are currently for sale by Graphenergy, there are two: “Graphenergy anticorrosive alkyd primer” and “Graphenergy anticorrosive epoxy primer”, each one designed according to different needs and conditions.

A. Graphenergy anticorrosive alkyd primer.

Provides high anticorrosive protection, resistance to UV rays and provides extraordinary adherence to the substrate. Ideal for the protection of industrial infrastructure, for the application of ferrous surfaces, both for interiors and exteriors. It is recommended for non-coastal areas or where humidity conditions are not high.

B. Graphenergy anticorrosive epoxy primer.

In addition, this coating offers extraordinary chemical resistance, with high wear resistance, resistance to UV rays, impermeability and greater adhesion, in order to improve the useful life of any metal surface or installation and reduce maintenance costs.

Graphene coatings provide enhanced properties and many more benefits, including:

  • Higher performance than existing coating technologies on the market today.
  • Fewer applied coating layers are required and with higher anti-corrosion protection.
  • Zinc reduction in formulations can reduce the amount by up to 50%.
  • Primers with greater chemical resistance and high thermal resistance.
  • Coatings with greater impermeability and non-stick effect (dirt does not adhere to it). Graphene oxide creates a two-dimensional network on the surface of the coating, which does not allow the anchoring or diffusion of water molecules or chemical substances, which allows the development of coatings with a hydrophobic effect, resulting in coatings that are easier to clean (See Fig.2).
Fig. 2. Behavior of coatings without and with graphene oxide, after subjecting them to a chemical attack (corrosive solution) for more than two hours.
  • Improves adhesion to the substrate. The primers with graphene oxide increase their adherence by up to 50% with respect to the control (Fig. 3).
Fig. 3. Primer adhesion test with and without graphene oxide.
  • More flexible coatings. The incorporation of graphene oxide not only improves adhesion, but also allows flexibility to the coating, allowing it to have high resistance to bending or greater resistance to fracture (Fig. 4).
Fig.4. Flexibility test in primary without and with graphene oxide.

Referencias

  1. Chang, C.-H. et al. Novel Anticorrosion Coatings Prepared from Polyaniline/Graphene Composites. Carbon N. Y. 50, 5044–5051 (2012).
  2. Fengjuan Xiao, Chen Qian, et al., et al., Progress in Organic Coatings, 125, 79-88 (2018); doi.org/10.1016/j.porgcoat.2018.08.027
  3. Karolina Ollik and Marek Lieder. Review of the application of graphene-based coatings as anticorrosion layers. Coatings 2020, 10(9), 883. 2020.
  4. Zhang J., Kong, G., Li S., Le Y., Che C., Zhang S., Lai D., Liao X. Graphene-reinforced epoxy powder coating to achieve high performance wear and corrosion resistance. 20:1448-4160, 2020.
  5. Ghosh Tuhin and Karak Niranjan. Mechanically robust hydrophobic interpenetrating polymer network-based nanocomposites of hyperbranched polyurethane and polystyrene as an effective anticorrosive coating. New J. Chem., 2020, 44, 5980-5994.

Nanotechnology and corrosion protection: the era of graphene oxide

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Nanotechnology and corrosion protection:

the era of graphene oxide

Corrosion is defined as the gradual deterioration of metallic materials and their properties, and occurs when the metal reacts with the surrounding environment to form rust or another chemical compound. In general, atmospheric air, humidity, rain, and aqueous solutions (chemical products) are the environments that are most frequently associated with corrosion problems.

Nowadays, corrosion damage is one of the most important problems to face for many industries in the world. It is estimated that corrosion causes economic losses of 3.4% of world GDP (about 2.5 billion dollars per year). However, there are three industries whose corrosion impact is more frequent and riskier for their processes: the chemical industry, the shipbuilding industry and the construction industry.

In the chemical industry, the use of chemical products is paramount within its operations, so equipment and machinery are in direct and constant contact with chemical substances, increasing maintenance and/or repair costs, affecting the industry budget and their production. In the case of the naval industry, humidity and salt are the main factors that contribute to the corrosion process and, consequently, the deterioration and affectation of its facilities, ships, containers and even merchandise. On the other hand, in the construction industry, both the machinery and the construction areas themselves can be affected by corrosion due to their exposure to the environment. Corrosion causes the metallic assets to weaken, generating mechanical failures, putting the work at risk.

Anticorrosive coatings are regularly used for protection against corrosion, humidity and fouling of installations, machinery and equipment. At a commercial level, there is a wide variety of anticorrosive coatings based on different additives and resins, their efficiency is generally associated with an increase in cost. However, the coatings still have low thermal and corrosion resistance and especially limited chemical resistance.

Graphene is currently the most revolutionary nanotechnological additive in the coatings and paints industry. The incorporation of graphene as an additive in coatings produces coatings with extraordinary protection against corrosion. Graphene creates pathways that are very tortuous, preventing water and oxygen molecules and/or chemical agents from diffusing to the surface of metal-based materials, resulting in metal protection against oxidation and corrosion. corrosion (Fig. 1).

Figure 1. Schematic representation of the tortuous path for oxygen and water molecules in polymer coatings with clay and graphene.

Graphene coatings provide many performance and anti-corrosion benefits, including:

  • Higher performance than existing coating technologies on the market today.
  • Fewer applied coating layers are required for greater benefits
  • Zinc reduction in formulations
  • Chemical resistance


Graphene and graphene oxide-enhanced anticorrosive coatings will replace traditional zinc-based coatings, which have several drawbacks, such as short life, high content of volatile organic compounds (VOCs), slow curing, high cost, sedimentation in storage.


Currently Energeia – Graphenemex®, a leading Mexican company in Latin America in research and production of graphene materials for the development of industrial applications, through its Graphenergy line, has launched a wide range of nanotechnological coatings with graphene. These coatings offer high anticorrosive protection, extraordinary chemical resistance, high wear resistance, resistance to UV rays, impermeability and greater adherence, in order to improve the useful life of any surface or installation and reduce maintenance costs.

References

  1. Chang, C.-H. et al. Novel Anticorrosion Coatings Prepared from Polyaniline/Graphene Composites. Carbon N. Y. 50, 5044–5051 (2012).
  2. Fengjuan Xiao, Chen Qian, et al., et al., Progress in Organic Coatings, 125, 79-88 (2018); doi.org/10.1016/j.porgcoat.2018.08.027
  3. Chaudhry, A. U., Mittal, V. & Mishra, B. Inhibition and Promotion of Electrochemical Reactions by Graphene in Organic Coatings. RSC Adv. 5, 80365–80368 (2015).
  4. Zhen, Z. & Zhu, H. Graphene: Fabrication, Characterizations, Properties and Applications. Graphene (Academic Press, 2018).

Protection against bacteria, viruses and fungi with graphene coatings

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Protection against bacteria, viruses and fungi

with graphene coatings

In less than 20 years the world has faced a series of abnormal phenomena caused by highly infectious pathogens. The easy and rapid transmission of infections forces us to seek increasingly efficient strategies to strengthen health services, in addition to representing a radical change in our lifestyle, where extreme hygiene techniques are in first place of importance to avoid the spread and massive contagion inside and outside hospitals.

Viral diseases of greater impact.

  • 2002-2003. Severe acute respiratory syndrome (SARS-Cov).
  • 2012. Middle East Respiratory Syndrome (MERS-Cov).
  • 2014- 2016. Ebola.
  • 2019- 2022. SARS-Cov-2.

>6.5 million deaths.

Dangerous bacteria for human health:

  • Staphylococcus aureus.
  • Streptococcus pneumoniae.
  • Pseudomonas aeruginosa.
  • Haemophilus influenzae.
  • Helicobacter pylori.

Common fungi in the domestic environment:

  • Aspergillus spp.
  • Cladosporium spp.
  • Alternaria spp.
  • Acremonium spp.
  • Epiccocum spp.
  • Penicillium spp.
  • Stachybotrys spp.

Graphene as an adjuvant in infection control

In 2018, Energeia- Graphenemex® launched the antimicrobial Graphenergy line, made up of two specialized vinyl- and vinyl-acrylic-based coatings with graphene oxide, whose antimicrobial potential is 400 times higher than common products, helping to keep surfaces free of fungi and bacteria for a long time.

In vitro studies and in a relevant environment carried out by the Laboratory of Pathology, Biochemistry and Microbiology of the Faculty of Stomatology of the U.A.S.L.P., showed that surfaces protected with antimicrobial Graphenergy remain free of microorganisms for more than 6 months, without the need for additional chemicals. Figure 1.

Fig. 1. Results at 2, 4 and 6 months on the protection of antimicrobial Graphenergy compared to a control group (No Graphene Oxide).
Important: A clean surface is in the range of 1-10 CFU/cm2.

In 2022, the strategic alliance between the companies Energeia-Graphenemex® and Oxical® is preparing to launch a new 100% natural coating, without toxic compounds (VOCs), highly waterproof, breathable and highly antimicrobial, made from high-quality and purity lime modified with Graphene nanoparticles, under the ecological Graphenecal brand.

Its extraordinary antimicrobial capacity is not only a great aid in keeping spaces free of microorganisms, but also protects surfaces against biodeterioration, particularly those with high historical value. Figure 2.

Fig. 2. Graphene-free lime paint has a microbial biofilm on more than 90% of its surface. The area covered with organic Graphenecal remained free of contamination for more than 100 days of incubation. The antimicrobial effect of organic Graphenecal is highly effective, with a reduction of microorganisms of 7 Log10.

Is graphene nanotechnology safe?

Yes, Graphenergy and Graphenecal antimicrobial coatings are as safe as any conventional paint or coating. The graphene and graphene oxide nanoparticles contained in its formulations do not shed or release toxic substances into the environment.

“Not all microorganisms are dangerous, but it is better to keep them away”

How do graphene materials work?


  1. Physical barrier- High impermeability. Graphene materials are usually presented in millions of blocks composed of 1 to 10 nanometric sheets similar to a pack of cards, with multiple sinuous paths between each sheet that act as an external barrier that suppresses the entry of essential nutrients for microbial growth.

  2. Graphene and its derivatives can act as electron donors or acceptors, altering the respiratory chain of the microorganism or extracting its electrons. This imbalance in the form of a nano-circuit is so fast that it does not give the microorganism time to recover and, therefore, inactivates it before adhering to the surface.

  3. Structural damage. The edges of the nanomaterial sheets act like small knives that damage or break the cell membrane of the microorganism, altering its functioning and preventing its viability.

Do graphene materials have antiviral activity?

The antiviral effect of graphene materials seems not to be very different from that described against fungi and bacteria. The hypotheses are directed towards an interesting synergistic effect between impermeability, structural damage and electrostatic interactions due to the positive polarity of some viruses (SARS-Cov-2) and the negative polarity of graphene oxide, in addition to its great protein-anchoring capacity.

Energeia- Graphenemex®is the pioneer Mexican company in Latin America focused on the research and production of graphene materials for the development of applications at an industrial level. In addition to adding value to its products with the multifunctional properties of Graphene and its derivatives, the company also aims to create strategic alliances to support innovative developments with graphene nanotechnology.

References

  1. García-Contreras R, Guzmán Juárez H, López-Ramos D & Alvarez Gayosso C. Biological and physico-mechanical properties of poly (methyl methacrylate) enriched with graphene oxide as a potential biomaterial. J Oral Res 2021; 10(2):1-9. Doi:10.17126/joralres. 2021.019
  2. UM.D. Giulio, R. Zappacosta, S.D. Lodovico, E.D. Campli, G. Siani, A. Fontana, L. Cellini, Antimicrobial and antibiofilm eficacy of graphene oxide against chronic wound microorganisms. Antimicrob. Agents Chemother. 62(7), e00547-18 (2018). https://doi.org/10.1128/AAC.00547-18
  3. H.E. Karahan, C. Wiraja, C. Xu, J. Wei, Y. Wang, L. Wang, F. Liu, Y. Chen, Graphene materials in antimicrobial nanomedicine: current status and future perspectives. Adv. Healthc. Mater. 7(13), 1701406 (2018). https://doi.org/10.1002/ adhm.201701406
  4. Sydlik SA, Jhunjhunwala S, Webber MJ, Anderson DG, Langer R. In vivo compatibility of graphene oxide with differing oxidation states. ACS Nano. 2015. 9: 3866
  5. Yang K, Zhang S, Zhang G, Sun X, Lee ST, Liu Z. Graphene in mice: ultrahigh in vivo tumor uptake and efficient photothermal therapy. Nano Lett. 2010. 10: 3318.
  6. Bhattacharya K, Farcal LR, Fadeel B. Shifting identities of metal oxide nanoparticles: focus on inflammation. 2014. MRS Bull; 39: 970
  7. Huang PJ, Pautler R, Shanmugaraj J, Labbé G, Liu J. Inhibiting the VIM-2 metallo-β-lactamase by graphene oxide and carbon nanotubes. ACS Appl Mater Interfaces 2015; 7: 9898.
  8. Moghimi SM, Wibroe PP, Wu L, Farhangrazi ZS. Insidious pathogen-mimicking properties of nanoparticles in triggering the lectin pathway of the complement system. Eur J Nanomedicine. 2015; 7: 263.
  9. Bhattacharya K, Mukherjee SP., Gallud A., Burkert SC., Bistarelli S., Bellucci S., Bottini, M., Star A., Fadeel B. Biological interactions of carbon-based nanomaterials: From coronation to degradation. Nanomedicine: Nanotechnology, Biology, and Medicine. 2016. 12. 333

Graphene oxide: a promising alternative in nanotechnology

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Graphene oxide:

a promising alternative in nanotechnology

Since graphene was isolated for the first time in 2004 by the Manchester group, this nanomaterial has proven to be the most revolutionary for the development of new applications at an industrial level.

Graphene has extraordinary electrical, optical, thermal properties and high mechanical resistance. The properties of graphene are attributed to its structure in the form of two-dimensional (2D) sheets, made up of hexagonally bonded carbon atoms and a thickness of one carbon atom.

Currently there are different methods of graphene production, these can be classified into two methods, according to their origin, the “bottom-up” method and the “top down” method. The “bottom-Up” method consists in the creation of graphene structures through building blocks (atoms, molecules), for example, by Chemical Vapor Deposition (CVD); and the “top down” method involves the production of graphene from the oxidation of graphite. Graphite is made up of sheets of graphene that are stacked on top of each other. The following diagram represents the process for obtaining graphene from the oxidation of graphite.

Schematic diagram of the process for obtaining GO, through the oxidation of graphite.

The graphite oxidation process begins with the addition of graphite in sulfuric acid (H2SO4), with constant mechanical stirring. Subsequently, potassium permanganate (KMnO4) is slowly added, producing a chemical reaction that allows the graphite (graphene sheets stacked on top of each other) to be chemically modified in its structure. When KMnO4 reacts with H2SO4, it forms manganese oxide VII (Mn2O7), which is a very selective oxidizing agent on double bond aromatic compounds, such as graphite. The oxidizing agent molecularly attacks the structure of each graphene sheet in the graphite, grafting oxygenated functional groups (with oxygen), such as epoxide groups (C-O-C) and hydroxyl groups (-OH), on each sheet, and carboxyl groups (-COOH, CO2H ) on the edges of each sheet, obtaining graphite oxide and graphene oxide (GO), see Figure 1.

Figure 1. Structure of graphene oxide

The incorporation of oxygenated functional groups allows a material such as graphite, which is highly hydrophobic (which repels water) and a good electrical conductor, to become graphite oxide and graphene oxide (GO), highly hydrophilic materials, that is, they mix and disperse easily with water (See Figure 2). GO is chemically similar to graphite oxide, but structurally differs in the arrangement and number of stacked sheets.

Figure 2. (a and b) Behavior of graphite and graphene oxide (GO) in water, c) GO sheet, Transmission Electron Microscopy (TEM).

The GO can be defined as a single exfoliated graphene sheet or stack of few sheets (3-4) that is functionalized with different oxygenated groups. Among its main characteristics is that it is hydrophilic, insulating and hygroscopic (absorbs moisture). On the other hand, graphene oxide sheets possess a large surface area and exhibit high mechanical strength and flexibility.

Applications

Graphene oxide has attracted great interest in various fields of science and technology, due to its remarkable mechanical, chemical, and thermal properties, among others. So numerous investigations began, to take advantage of the properties of graphene oxide.

In 2011, the first investigations of the use of GO as a precursor in the large-scale production of graphene emerged, for use as filler/reinforcement material/in polymeric matrices, such as high-density polyethylene (HDPE) and low-density polyethylene (HDPE). density (LDPE).

By 2014, GO was considered feasible for use as a flame retardant agent. Research is still ongoing to functionalize it with different polymeric materials.

In 2017, the first reports of the manufacture of GO-based membranes began, since it is impermeable to gases and liquids, showing its ability to filter small particles, organic molecules and even its use for seawater desalination.

In 2018, Energeia-Graphenemex started research on graphene oxide as a new additive for the production of anticorrosive and antimicrobial coatings. By 2019, studies of graphene oxide in coatings with antibacterial behavior increased, associated with the fact that GO is capable of penetrating the cell membrane of bacteria, producing oxidative stress and inhibiting their reproduction.

In particular, the functionalization of GO allows it to be applicable in biological systems, development of biosensors for the identification of specific molecules, drug delivery systems, among others.

Energeia – Graphenemex®, a leading Mexican company in Latin America in research and production of graphene materials for the development of industrial applications. It has extensive experience in the production of graphene oxide (GO) on a large scale, with different degrees of oxidation and high quality for use in different applications and industries. Currently, it uses graphene oxide in the production of concrete additives and anticorrosive and antimicrobial coatings that are marketed under the Graphenergy brand.

References

  1. M. Fang, K. Wang, H. Lu, Y. Yang y S. Nutt, «Covalent polymer functionalization of graphene nanosheets and mechanical properties of composites,» Journal of Materials Chemistry, vol. 19, pp. 7098-7105, 2009.
  2. B. Dittrich, K.-a. Wartig, R. Mülhaupt y B. Schartel, «Flame-Retardancy Properties of Intumescent Ammonium Poly(Phosphate) and Mineral Filler Magnesium Hydroxide in Combination with Graphene,» Polymers, vol. 6, pp. 2875-2895, 2014.
  3. Y.-j. Wan, L.-x. Gong, L.-c. Tang, L.-b. Wu y J.-x. Jiang, «Mechanical properties of epoxy composites filled with silane-functionalized graphene oxide,» COMPOSITES PART A, vol. 64, pp. 79-89, 2014.
  4. J. Wang, C. Xu, H. Hu, L. Wan, R. Chen, H. Zheng, F. Liu, M. Zhang, X. Shang y X. Wang, «Synthesis , mechanical , and barrier properties of LDPE / Graphene nanocomposites using vinyl triethoxysilane as a coupling agent,» J. Nanopart Res, vol. 13, pp. 869-878, 2011.

Graphene, the material of the future in coatings and paints industry

Posted on | by Energeia Graphenemex

Graphene, the material of the future

in coatings and paints industry

Graphene is currently the most revolutionary nanotechnological additive in the coatings and paints industry.

Coatings are regularly used for decorative purposes and for surface protection, especially for protection against corrosion, humidity, fouling, mechanical wear, among others. At a commercial level, there is a wide variety of coatings based on different types of resins and additives, their efficiency is generally associated with an increase in cost. However, the coatings still have low resistance to corrosion, abrasion and limited chemical and thermal resistance.

Therefore, the coatings industry, like many other industries, is constantly researching and developing new technologies for the formulation and application of new and better coatings.

Since 2004, when the graphene nanomaterial was first isolated, scientists in the coatings industry have been looking for ways to use graphene as an additive to improve the performance and technology of coatings in different application areas.

Graphene has unique properties, mainly attributed to its structure in the form of two-dimensional (2D) sheets, formed by carbon atoms linked in a hexagonal manner and a thickness of one carbon atom. This nanomaterial has extraordinary properties, which include high electrical and thermal conductivity, and high mechanical resistance. In addition, it possesses other distinctive properties, including gas impermeability, chemical resistance, antibacterial potential, and high surface area.

Graphene’s carbon-based composition and its compatibility make it a viable additive for organic polymeric coatings.

Among the advantages offered by the use of graphene is its ability to incorporate new or improved characteristics in the coatings. Different types of multifunctional coatings can be developed, such as:

  • Anticorrosive coatings

One of the main uses of graphene coatings is protection against corrosion. Graphene creates pathways that are very tortuous, preventing water and oxygen molecules and/or chemical agents from diffusing to the surface of metal-based materials, resulting in metal protection against oxidation and corrosion. corrosion.

  • Fire retardant coatings

Conventional additives based on halogens (bromine and chlorine), as well as phosphorous, melamine and inorganic compounds, are used to improve the fire resistance of coatings, however, these materials are toxic to humans and the environment. On the other hand, the high content of these flame retardants can cause the deterioration of other properties in the coatings.

Therefore, the application of graphene as a new additive in coatings can reduce or eliminate the use of conventional flame retardant additives, it can also provide the coating with better performance against extreme temperatures for a longer time and with better mechanical stability.

  • Coatings resistant to wear or abrasión

Graphene has proven to be a potential candidate for wear, abrasion and scratch resistant coatings. Graphene is the lightest material and two hundred times more resistant than steel, in addition, graphene has a high capacity to withstand large pressure differences and high mechanical resistance.

  • Antifouling coatings

Graphene is a good candidate for use as an anti-stick agent. Its application reduces the problem of fouling and the deposition of organic and inorganic materials in the hulls of ships, ships or marine vessels, oil platforms, among others. This type of application is mainly attributed to the hydrophobic (water repellent) and barrier properties of graphene.

  • Antimicrobial coatings

The use of graphene or graphene oxide sheets as an antimicrobial agent is innovative, since there are studies that have shown a strong antimicrobial activity against a wide variety of microorganisms, including Gram +, Gram – bacteria and fungi.

Associated with the fact that graphene materials are capable of penetrating the cell membrane of microorganisms, producing oxidative stress and inhibiting their reproduction.

Globally, research and development of graphene-based coatings continues. Currently there are several companies and institutions that have made improved formulations with graphene for coatings, among which the following stand out:

  • Applied Graphene Materials, based in the United Kingdom, in collaboration with the American company Sherwin-Williams, are developing graphene-based anticorrosive paints. Its objective is to incorporate graphene in different formulations, especially in maritime paint for use in ship hulls to protect them from corrosion.
  • The Sixth Element Materials, a Chinese company that focuses on the research, development and sale of graphene materials, has launched a graphene-zinc-based anticorrosive primer for offshore wind power towers.
  • Graphenstone, a Spanish company, has developed ecological paint that combines graphene and lime technology. Obtaining paints with greater resistance, flexibility, quality and a longer life span compared to conventional lime-based paints.

Energeia – Graphenemex®, a leading Mexican company in Latin America in the research and production of graphene materials for the development of industrial applications, through its Graphenergy line, has launched a wide range of nanotechnological coatings with graphene. These coatings offer high anticorrosive and antimicrobial protection. In addition, it provides high resistance to wear, resistance to UV rays, impermeability and extraordinary adherence, in order to improve the useful life of any surface or installation and reduce maintenance costs.

Graphene coatings, in addition to having anticorrosive protection, can provide greater chemical resistance, UV resistance, higher thermal performance in a wide range of temperatures, as well as more flexible and crack-resistant coatings.

References

  1. DuMée, L.F., et al., Carbon, 87, 395–408 (2015); doi:10.1016/j.carbon.2015.02.042.
  2. Wang, E.N., et al., Nano Lett., 15 (5), 2902–2909 (2015).
  3. J. Chen, H. Peng y X. Wang, Nanoscale, vol.6, pp. 1879-1889, 2014
  4. Md J. Nine, Martin A. Cole, Diana N.H. Tran, and Dusan Losic, J. Mat. Chem. A, 2015.
  5. Sachin Sharma Ashok Kumar, Shahid Bashir, K. Ramesh, S. Ramesh, Progress in Organic Coatings, 154, (2021)

Graphene and its impact on the packaging industry

Posted on | by Energeia Graphenemex

Graphene

and its impact on the packaging industry

According to data from the World Bank, every year in Mexico 24 million tons of food are wasted. This means that 34% of the country’s production is not only NOT consumed, but also generates an average expense of 491 billion pesos.

This impact is not only economic, but it is a problem that extends to the social sphere, due to the well-known food crisis and to the environment, due to the high water requirements for food production processes that will not be used and whose decomposition will contribute considerable CO2 emissions that contribute to global warming.

According to the Food and Agriculture Organization of the United Nations, the loss and food waste exceeds 1,300 million tons per year.

Within this multifactorial problem, the container and packaging industry, also known as “packing”, is a crucial actor considering that there are unavoidable conditions such as temperature, humidity, lighting, oxygen and numerous handling practices throughout the entire supply chain. production of food, which affect its quality, shelf life and acceptability by consumers.

In the search for solutions to improve the quality of packing products and, consequently, their content, nanotechnology has been a great ally. For example, to avoid microbial contamination, nanoparticles of silver, titanium dioxide, copper oxide, carbon nanotubes or magnesium oxide are used; to improve the mechanical or barrier properties, it is common to use nanoparticles of silicate, clay, polyamide, iron or iron oxides, cellulose nanofibers and for other needs there are nanoparticles of tungsten, molybdenum, barium sulfate, barium titanate , chitosan, zeolites, activated carbon, etc.

Graphene nanoparticles are mainly made up of carbon, like graphite and diamond, but with multifunctional characteristics. This means that they do not have a single function, but rather, unlike other nanoparticles, Graphene, due to its extraordinary physical and chemical properties, can be used for different purposes, for example, to design lighter and more resistant products, with greater impermeability against liquids and gases, in addition to protecting against microbial contamination and against UV radiation, among other properties that substantially improve the performance of the compounds with which it is combined.

“Graphene has crossed the limits of laboratories to reach commercial applications to combat the main enemies of food”, these are some examples of what is being developed for the Packing industry:

Tetra Pak
The Swedish company Tetra Pak, leader in research and development in the packaging sector, through the European Graphene Flagship project, studies the use of Graphene for the manufacture of products with low environmental impact to reduce the carbon footprint, improve the performance of materials, add properties and optimize recyclability.

Applynano
The Spanish company Applynano uses nanomaterials, including graphene oxide, to promote the durability and recyclability of plastics, as well as to improve antimicrobial, thermal, and electrical properties, among others.

Plastic Technology Center (Andaltec)
The Technological Center of Plastic (Andaltec) within the European project Grafood, had the initiative to use derivatives of Graphene for the development of active packaging to increase the shelf life of food and reduce food waste.

Energeia – Graphenemex®
The Mexican company Energeia – Graphenemex®, through the polymer division Graphenergy Advanced Graphenic Solutions, promotes the use of Graphene and its derivatives as nano-reinforcement of plastic for different industries. Among the benefits it offers for the packing industry are mechanical resistance and resistance to degradation by UV radiation, greater barrier effect and interesting antimicrobial properties, highly promising for prolonging the life of products and their contents. Likewise, in addition to adding value to its developments with the multifunctional properties of Graphene and its derivatives, the company also aims to support other innovation projects with graphene nanotechnology, while seeking to collaborate with the circular economy to improve the quality of new and recycled plastic materials, to reduce the consumption of single-use products.